Method for Cooking Foods, and Apparatus Implementing the Method

ABSTRACT

Provided is a cooking apparatus, preferably including a plurality of heating plates for contact cooking. The cooking time is determined by selecting a desired degree of cooking of the food. After estimating the surface area occupied by the food on one of the heating plates, said cooking time is calculated on the basis of the desired degree of cooking, the thickness of the food, and the surface area occupied by the food

The present invention relates to an apparatus for cooking food items by contact with at least one heating plate, and an associated method.

Among these apparatuses, particularly well known are the dual-surface grills which comprise lower and upper heating plates between which one or more food items to be cooked are positioned. The food items are positioned horizontally on the lower heating plate. The food items can be meat, fish, vegetables or other.

DE 4302190 and WO 2007/149063 disclose a cooking method and device that are illustrative of the prior art.

However, these known solutions do not make it possible to obtain an optimized organoleptic result. They do not make it possible to provide an automatic cooking cycle that is truly favorable to the food and to the taste of the user.

Thus, the invention aims to provide a method for implementing an apparatus for cooking a food by contact with at least one heating plate, and the associated apparatus, making it possible to control the cooking of the food items automatically, according to a cooking process that is optimized to obtain:

-   -   a favorable organoleptic result,     -   an accurate cooking temperature at the core,     -   a texture and color to the taste of everyone.

In order to tend toward satisfying at least some of these objectives, two alternative approaches, but approaches that evolve from one and the same concept, are proposed.

According to the first approach, there are provided:

-   -   storage in a memory of the apparatus of different internal         cooking temperatures (X) for the food,     -   to achieve an internal cooking of the food to a greater or         lesser degree as then desired by a user, a selection by the user         of one of said stored temperatures (X) and a placing of the food         in contact with the heating plate or plates,     -   then, a calculation of the cooking time for the food as a         function (at least) of the selected temperature (X).

To avoid overcooking should the user forget or not pay attention to the probable state of progress of the cooking cycle, it is preferred that, at the end of the calculated cooking time (T), there is favorably an indication by the apparatus that the desired cooking has been achieved.

Posssibly, this indication could be replaced or complemented (and this will be valid for what follows) by an immediately automatic shutdown of the apparatus or a setting thereof to simply keep the cooked food hot. However, then, the thermal inertia could affect the quality of the cooking if the user does not quickly remove the food from the apparatus.

To favor the expected cooking in a way that is deemed safest, it is recommended to carry out:

-   -   a measurement of the thickness (Y) of the food then positioned         against said heating plate and/or an estimation of the surface         area (Z) occupied by this food on the heating plate,     -   and the calculation of the cooking time (T) for the duly         positioned food, based:         -   in addition to the selected cooking temperature (X),         -   on the thickness (Y) of the food, and/or on the surface             area (Z) occupied by the food.

According to the second approach, there are proposed:

-   -   again, storage in a memory of the apparatus of different         internal cooking temperatures (X) for the food,     -   to achieve an internal cooking of the food to a greater or         lesser degree as then desired by a user, once again a placing of         the food in contact with the heating plate or plates, but then:     -   a calculation of a first cooking time (T) for the duly         positioned food, as a function (at least) of the lowest         temperature (X) out of those stored in memory,     -   at the end of said calculated first cooking time (T), an         indication to the user, by the apparatus, that the corresponding         cooking has been achieved, then:     -   if the user does not remove the food, the application by the         apparatus of a calculated second cooking time (T) for the food,         as a function of the second in ascending order of said         temperatures stored in memory (X),     -   at the end of this calculated second cooking time (T), another         indication to the user, by the apparatus, that the corresponding         cooking has been achieved,     -   and so on.

Regardless of whether the first or second approach is applied, the storage in memory will be able to be a prestorage in the factory, before the first operational use of the apparatus.

Thus, the risks of errors and the intervention of the user will be limited.

According to the second approach, again to favor achieving the expected cooking that is deemed safest, it is similarly recommended to carry out, as already described:

-   -   a measurement of the thickness (Y) of the food then positioned         against said heating plate and/or an estimation of the surface         area (Z) occupied by this food on the heating plate,     -   the calculation of the cooking time (T) for the duly positioned         food, based:         -   in addition to said internal cooking temperature (X) out of             those stored in memory,         -   on the thickness (Y) of the food and/or on the surface             area (Z) occupied by the food.

To favor the consideration of the thickness parameter and/or avoid, for example, having to turn over the food during cooking, which will be necessary with an apparatus like a cooking pan comprising only one heating plate, in this case the cap of this cooking pan that is placed on the heat source (electric, induction or similar plate, or even gas burner), provision is made, during said operation of the apparatus, for the food to be positioned between a plurality of said heating plates, on their contacts. A grill with electric heating elements is then particularly targeted.

Although, in any case, at least a part of the objective of automatic cooking can be achieved with this calculation of cooking time (T) of the food in contact with the heating plate or plates, possibly only as a function of said temperature(s) (X) stored in memory, it is however recommended that the calculation of the cooking time (T) for the food be a function of said surface area (Z) occupied by the food, which will then be obtained by heating plate temperature measurements.

To favorably limit the possible calculation drifts and reliably manage, in a minimum of time and as simply as possible, the estimation of said surface area (Z), it is recommended to measure, by at least one temperature sensor and following the placing of the food in contact with the heating plate or plates, the temperature of the or of one of the heating plate(s), and to compare the variation of the measured temperature evolving therefrom to at least one reference threshold.

Also in the interests of proven reliability, it is also recommended that the cooking time (T) for the food be obtained by a quadratic or linear correlation calculation method.

In order to also automate in an optimized manner the operation of the apparatus, by avoiding untimely starts not justified by the presence of a food and the will of the user, it is recommended that the implementation method concerned here comprise, before the food is placed in contact with the plate or plates, a step (A) of preheating of the apparatus followed by the step (B) of cooking of the food, the start of which is detected by a lowering against a predetermined threshold of the temperature of the or of one of the heating plate(s).

Once again to refine and make the implementation process reliable, with a view to optimized cooking quality, it is recommended:

-   -   that the calculation of the cooking time (T) for the food be a         function of said surface area (Z) occupied by the food and, to         estimate this surface area,     -   that a single temperature sensor be used, which, following the         placing of the food in contact with the plate or plates, will         measure the temperature of at least one of said plates, away         from the area of contact of the food,     -   and that the measured temperature variations which evolve         therefrom or a time that is then calculated until a         stabilization of the measured temperature, after said placement         in contact, be compared to at least one threshold.

For said comparison, it is recommended to use the observed fact that there is a relationship between the surface area occupied by the food and:

-   -   the time observed after introduction of the food until the         stabilization, also observed, of the temperature drop following         the hot plate(s)/food contact; namely the passage with         (substantially) nil slope of the measured plate temperature,     -   or this measured plate temperature drop (in terms of amplitude         or in terms of minimum reached), following said placement of the         food,     -   or a rate of drop of this temperature.

Alternatively, a method has been devised whereby, the calculation of the cooking time (T) for the food then being a function of said surface area (Z) occupied by the food:

-   -   to estimate this surface area, a number of temperature sensors         are used which, following the placing of the food in contact         with the plate or plates, will measure the temperature of at         least one of said plates, in the area of contact of the food,     -   and the measured temperature variations which evolve therefrom         or a time that is then calculated until a stabilization of the         measured temperature, after said placement in contact, are         compared to at least one threshold.

A high organoleptic quality of the food will be able to be achieved if, as proposed elsewhere, during the step or steps of estimation of the surface area (Z) occupied by the food and/or of the thickness (Y) of the food, and/or of the calculation of the cooking time (T) for the food, there is marking of the food, with an electrical power delivered by the apparatus which is maximum.

In fact, a marking will thus be favored that:

-   -   is rapid at the start of cooking for a better retention of the         water in the meat, and therefore gives a better and more juicy         character,     -   is sufficiently sharp, while being able to prevent an harmful         carbonization, to add taste and crustiness without generating         carcinogenic compounds.

In order to refine the way in which the method is implemented for the purpose of quality in another way, it is also recommended that at least one of the following steps can be provided:

-   -   selection of the category of the food to be cooked, and/or     -   selection of the frozen state of the food, and/or     -   selection of a desired grill marking of the food.

On this subject, it is also recommended that the cooking temperature (θ) for the food after and the preheating temperature (θ′) be a function of said selection made.

To further optimize the process of implementation of the method in another way, it is proposed that, after having positioned the food in contact with the plate or plates, it be possible to:

-   -   measure the thickness (Y) of the food and,     -   as a function of this measurement, trigger or not the cooking of         the food by the calculation of the cooking time.

It is recommended, in the interests of accuracy and of simplicity and reliability of implementation, that the thickness (Y) of the food be determined by a measurement of the distance separating the heating plates between which the food is positioned.

Providing for consideration of the parameters X, Y and Z makes it possible to optimize the quality of the cooked product. The cooking time (T) will increase with the surface area of the heating plate occupied and the thickness (Y) of the food is high. The cooking time (T) will thus depend on the volume of the food put in place.

In addition to the abovementioned method with all or some of the features presented, one object of the invention relates to a cooking apparatus comprising:

-   -   at least one heating plate for heating the food by contact and,         to therefore achieve an internal cooking of the food to a         greater or lesser degree as desired by a user:     -   a memory for storing different internal cooking temperatures (X)         for the food,     -   means for measuring the thickness (Y) of the food then         positioned in contact with the heating plate or plates and/or         means for estimating the surface area (Z) occupied by this food         on the or one of the heating plate(s),     -   means for calculating at least one cooking time (T) for the duly         positioned food, based:         -   on at least one of the internal cooking temperatures (X) out             of those stored in memory, and         -   on the thickness (Y) of the food, and/or on the surface             area (Z) occupied by the food;     -   and means for indicating to the user, by the apparatus, that the         corresponding cooking has been achieved.

In the interests of accuracy and simplicity and reliability of implementation, it is recommended that the means for estimating the surface area (Z) occupied by the food on the heating plate comprise at least one temperature sensor measuring the temperature of the or of at least one of the heating plate(s).

Assuming in particular a single-sensor option, with optimized control of the cooking, it is also recommended that the temperature sensor be situated in an area not likely to be in contact with the food.

Again with a view to optimizing the apparatus and therefore the process of implementing its operating mode, it is proposed that the means for calculating the cooking time (T) for the food comprise a microcontroller configured to determine the slope of the temperature curve obtained from the measurements of the temperature sensor(s).

Other features and advantages of the invention will emerge clearly from the following description, in the case of a common use of the abovementioned three parameters (X, Y, Z), and in an indicative and in no way limiting manner, with reference to the attached drawings, in which:

FIG. 1 represents an example of cooking process according to one embodiment of the invention;

FIG. 2 represents a lower shell of a cooking apparatus provided with two temperature sensors, according to one embodiment of the invention;

FIG. 3 represents the two temperature curves measured by two temperature sensors of one of the enclosures, such as the lower shell, and the temperature curve measured at the core of the food as a function of time,

FIG. 4 shows an example of cooking kinetics ensuring a cooking with marking, independently of the number of food items on the plate, with measurement of temperatures by a single sensor,

FIGS. 5, 6 respectively show the trend of the temperature of the temperature sensor provided, as a function of time and of the surface area occupied by the food, and the trend of the slope of the curve 2 as a function of time and of the surface area occupied,

FIGS. 7, 8 show a cooking apparatus of grill type making it possible to implement the method that is the object of the invention.

What is described below is intended to be implemented in a cooking apparatus. Such an apparatus here comprises two shells articulated relative to one another, i.e. a lower shell 9 and a upper steel 90; see FIGS. 7, 8. The lower shell 9 comprises a lower heating plate 61 and the upper shell comprises an upper heating plate 63. Each shell comprises a heating resistor 10 positioned between the heating plate and the bottom of the shell.

In the normal position of operation of the apparatus, the food or food items to be cooked are positioned horizontally on the lower heating plate which extends along a horizontal plane. The food can be meat, or other food.

As illustrated in FIG. 1, the cooking method comprises a preheating A) of the apparatus followed by a cooking B) of the food for a time (T).

FIG. 1 represents a process of cooking a non-frozen meat as an example. The curve 1 represents the trend of the temperature measured at the core of the food as a function of time. It was acquired in the factory and does not necessarily exist in the apparatus marketed. At least some of these points are, however, entered into memory 72 of the apparatus. The curve 2 represents the trend as a function of time of the temperature of one of the heating plates, which is measured during commercial operation of the apparatus. The x axis 3 represents the time in seconds, the y axis on the left 4 represents the measured temperature of the heating plate concerned, such as 63, and the y axis on the right 5 represents the temperature measured at the core of the food. The curve 6 represents the heating cycle as a function of time (consumed power). During the step A), the measured temperature of the plate rises rapidly to a level 7 corresponding to a preheating temperature. In the example 2, this temperature is approximately 230° C. Once this is reached, the food is placed on the lower heating plate. The high contact temperature makes it possible to make a marking on the food. A crust is then formed.

The setting of the food in the heating apparatus corresponds to the start of the step of cooking of the food B). The measured temperature of the heating plate (curve 2) drops to a temperature stabilization level 8, corresponding to approximately 150° C. in the example.

By way of confirmation (since a priori not available in the apparatus), the curve 1 shows that the temperature of the food rises in the meantime gradually to a temperature which is a function of the category of the food, or even of its frozen state.

Below is a first block diagram of controlled cooking:

Before this block diagram scheme is implemented, with, for example, the apparatus schematically represented in FIG. 7, it is understood that in the factory (therefore before marketing of the apparatus), in particular different internal cooking temperatures (X) for the food (preferably for several foods) have been stored in the memory 72 of the apparatus, allowing for example, at least one given food to be cooked to the core successively rare, medium-rare and well cooked.

This having been done and the apparatus sold, when its user goes to use it, the following steps will be implemented:

-   -   powering up of the apparatus 1, for example by pressing on an         on/off button 70;     -   via the interface 67 of the apparatus, and in the menu that the         latter then displays, selection on the apparatus, by the user,         preferably first of a food category to be cooked (choice for         example between meat and fish), then, here, of a degree (X) of         internal cooking desired for the food, out of several available         (if provided);     -   determination:         -   of the temperatures θ: maximum preheating temperature             (before placement of the food) given the food category, if             the latter can be selected, and θ′: minimum or final cooking             temperature for the food (after he or she has placed the             food), again taking into account its category, if provided,         -   and of the duty cycle: evolutions of the electrical energy             supplied to the elements 10 from the source provided (such             as the mains); definition and application of the variations,             which can be binary—maximum or zero, of this energy; see             curve 6;     -   preheating of the cooking apparatus (step A), via the resistors         10, with application of a predetermined preheating time defined         in factory tests, then entered into memory 72 and which makes it         possible to achieve the stabilized temperature θ for the planned         interval;     -   with the cooking apparatus open, placement of the food;     -   closure of the cooking apparatus; this will preferably be         necessary to activate the start of the cooking of the food (step         B), with, then, preferably automatically, a measurement of the         thickness (Y) of the food introduced between the plates 61, 63;     -   the apparatus then automatically detects an abrupt lowering of         the measured temperature of the heating plate concerned (contact         with the food), after which the temperature is substantially         stabilized; see zone 8, FIG. 1 or 3. Preferably, this start of         cooking step B) will be detected:         -   as a function of this lowering of measured temperature(s)             (in terms of time, speed, slope, etc),         -   and by comparison with one or more predetermined thresholds             of the drop detected;     -   from this/these temperature variation(s) measured on the plate         concerned of the grill, there may then be an estimation of the         load (or surface area occupied by the food): abovementioned         parameter (Z);     -   still preferably at the start of this cooking step, there is         also estimation/calculation by the apparatus of the required         cooking time (T). This time is therefore that, indicated for         example in FIG. 1 (T), between the moment when the food is         placed in contact with the heating plate or plates and that when         it is removed therefrom, at the end of cooking. The origin         moment can typically be that of the closure of the apparatus, if         it is a grill, followed almost immediately by the detected         measured plate temperature drop. The end moment is also that         when the announcement that the cooking has been achieved is made         by the apparatus. The expected internal cooking         temperature/degree (X) is achieved;     -   via, for example, a microcontroller 73, 75, and indicator 79         accessible to the user, provision can then be made for the user,         at the end of the calculated time, to be informed by the         apparatus that the expected degree (X) of cooking has been         achieved; the user is thus prompted to remove his or her food;     -   the apparatus can then, for example, automatically keep the food         hot while waiting for the user to open the apparatus;     -   the apparatus can finally be powered down, for example via the         switch 70.

Thus, the end of cooking is established at the end of the estimated/calculated time T, when, once the food has been placed in the preheated apparatus, the measured temperature, after having dropped because of this food, is stabilized (zone 8, FIG. 1 or 4), for example between two values for which the difference has been predefined and entered into memory 72.

In addition to the above, the interface 67 with the user may make it possible to select from the menu the frozen state of the food (frozen or not) and/or the amount of grill marking desired (strongly marked or other).

The interface 67 can be a touch screen.

In the above block diagram scheme, the cooking time (T) for the food in the abovementioned step B) is determined according to a process in which the steps set out below have been carried out:

-   -   a step of measurement of the thickness (Y) of the food,     -   a step of estimation by the apparatus of the surface area (Z)         occupied by the food on one of the heating plates,     -   a step of calculation in the apparatus of a cooking time (T) for         the food, as a function:         -   of the degree (X) of internal cooking of the food,         -   of the thickness (Y) of the food,         -   of the surface area (Z) occupied by the food.

The degrees (X) that can be selected will be able to correspond to respectively rare, medium and well-done cooking cycles. Each case will, in memory 72, have a corresponding cooking temperature taken from the curve 1, in the factory. Thus, it will be possible to have three values of the parameter, respectively 55° C., 65° C. and 75° C.

To measure the thickness (Y) of the food, the apparatus can be provided with sensor means 65 detecting the mean distance between the lower and upper heating plates, 61, 63, and in particular their relative separation when the food is introduced between them. It is then possible to obtain a food thickness which is a function of the relative displacement distance of the plates between them, when the apparatus is closed.

In FIG. 7, it can be seen that these heating plates are rotationally mobile relative to one another. When the upper heating plate is in horizontal position after having been displaced toward the lower heating plate, a positioning mechanism 66 can linearly and vertically displace the upper heating plate (by moving one of these plates closer to or further away from the other) until there is contact with the interposed food.

As an example, the sensor means 65 can comprise at least one optoelectronic sensor or one inductive proximity sensor. It could alternatively be a forced sensor measuring, for example, the force on a spring blade via a strain gauge, or a magnetic incremental position sensor using the Hall effect (again, distance measurement).

Once the preheating is finished, the automatic triggering, by the apparatus, of the cooking step will preferably occur only if the sensor means 65 measure a value that is neither zero nor “infinity”.

In FIG. 8, it can be seen that the positioning means or mechanism 66 comprise arms 660, 661 mounted articulated between the lower 9 and upper 90 shells. These arms, here two, 660, 661, are fixed, here laterally, close to one of the edges of each of the enclosures, such that two parallel axes of rotation 9 a, 90 a (horizontal) passing through the fixings of the arms 660, 661 are defined, for the relative movements between the heating plates. Opposite, a handle 81 fixed to one of the enclosures, here 90, assists in the maneuver.

During the abovementioned step of estimation of the surface area (Z), means for estimating this surface area determine whether the heating plate, provided with the load sensor(s), is fully loaded, partially loaded, or not loaded (cooking apparatus empty). This estimation can therefore be obtained from variations of temperature data measured on one (at least) of these plates.

The step will preferably comprise, advantageously for a predefined time (T) which begins from the detection of the start of the cooking step B):

-   -   a sub-step of measurement of the temperature of the heating         plate fitted (upper plate 63, FIG. 7),     -   then a sub-step of determination of this surface area (Z) as a         function:         -   a) of the calculated time to achieve a substantially more             stabilized slope (abovementioned zone 8, FIGS. 1, 3) of             trend of this measured temperature,         -   or b) of a drop in this temperature compared to a             predetermined threshold (value(s) in amplitude on reaching a             minimum temperature and/or in terms of slope(s), [B, see             below],             with, in the case a), the existence of a relationship             between the surface area and the quantity of energy to be             provided to compensate for the heat losses due to the             placement of the food.

The calculation of this parameter will be able to be performed by a calculating means such as a microcontroller with which the apparatus is equipped.

With a multi-sensor solution, such as, for example, with the two temperature sensors 11 a, 11 b, shown in FIG. 2 (even if it will be preferred to place a first sensor centered on a side (such as 11 a, FIG. 3), and a second off-center), comparisons, preferably of slope values, calculated for one and the other of these sensors, with a predetermined threshold, stored in memory 72, will be able to make it possible to define the values of the parameter (Z) to be used.

With the solution with two temperature sensors 11 a, 11 b shown in FIG. 2, and if the parameter retained is the slope, the following thresholds will be able to be considered:

-   -   if slope>−0.5° C./s for the two sensors=>surface area Z         little/not loaded=>value Z1,     -   if slope <−0.5° C./s for one of the sensors, with=>surface area         Z averagely loaded=>value Z2,     -   if slope <−0.5° C./s for the two sensors=>surface area Z fully         loaded=>value Z3.

As temperature sensor(s), it will be possible to choose probes with negative temperature coefficient (NTC). They will be able to be housed behind the heating plate which will cover them internally.

Computation means then make it possible to calculate the cooking time (T) for the food as a function of the degree of the internal cooking temperature (X) desired, here selected, for the food, of the thickness (Y) of the food, and/or of the surface area (Z) that it occupies.

This cooking time (T) for the food can be determined by a quadratic correlation calculation method with the following second degree function:

T(X,Y,Z)=A1+A2*X+A3*Y+A4*Z+A5*X ² +A6*Y ² +A7*Z ² +A8*X*Y+A9*X*Z+A10*Y*Z.   (1):

The coefficients A1, A2, A3, A4, A5, A6, A7, A8, A9 and A10 are predefined for each menu, for predefined temperature conditions. They are stored in storage means (such as the memory 72). They are constants.

As a variant, the cooking time (T) for the food can be determined by a linear correlation calculation method with the following first degree function:

T(X,Y,Z)=B1+B2*X+B3*Y+B4*Z   (2):

The coefficients B1, B2, B3 and B4 are predefined for each menu, for predefined temperature conditions. They are stored in said storage means (memory 72 for example). They are constants.

The linear correlation method is preferred to the other because, although less accurate, it requires only four coefficients. Here, it is more efficient.

Regarding the estimation of the surface area occupied by the foods, the possibility of an estimation of the surface area (Z) via (at least) two temperature sensors (values Z1, Z2, etc), has been described above.

Another possibility consists in using only a single energy sensor (item 11, FIG. 7) which can be a temperature probe placed, as previously, in contact with one of the heating plates. Favorably, this sensor will be offset (toward) the periphery of the heating plate concerned, facing an area of the plate where food should (or can) not be placed. The sensor will be able to fulfill two functions, in conjunction with the microcontroller(s):

-   -   regulating the temperature of the plate,     -   measuring the quantity of energy to be supplied to compensate         for the losses linked to the presence of the food(s) on the         plate. Assuming that the food items are steaks (see FIGS. 4-6),         it will be possible to correlate this with the number of such         steaks present, cooking on the plate, or the size of the surface         area occupied.

Thus:

-   -   a slope beyond a first threshold retained and stored in memory         72 will be able to correspond to a heating plate fully occupied         by the food,     -   a slope below a second threshold will be able to correspond to         an unoccupied heating plate,     -   and a slope between the two thresholds will be able to         correspond to a partially occupied heating plate.

To illustrate this, FIG. 4 shows an example of cooking kinetics established on the following bases: cooking of three steaks cut from a topside round, common thickness of 29 mm, identical surface areas of the plates 61, 63 substantially fully occupied (except just at the periphery where the temperature sensor 11 is located; FIG. 7), expected core temperature (at the end of cooking) of approximately 60° C., cooking time approximately 23 min (calculated).

This kinetic could be considered to be valid regardless of the surface area estimation method used; it could therefore replace the illustration of FIG. 1 where the curve 2 concerned a multi-sensor application.

In FIG. 4, the x axis represents the time in seconds, the y axis on the left 4 represents the temperature (° C.). The y axis on the right 50 represents the thickness (mm) of the food. The curve 21 represents the trend of the thickness of the food(s) present on the heating plate as a function of time. The trend of the curve 2 is comparable to that of FIG. 1 (see comments above). After the step A (=A1+A2) of preheating, the placing of the food in the heating apparatus corresponds to the start of the step B(=B1+B2) of cooking of this food.

The following occurs therein:

-   -   a cooking cycle in two phases:         -   a phase B1 of marking;         -   a phase B2 of cooking at lower temperature, to allow time             for the calories to migrate to the core without risking             charring the periphery;     -   a marking time approximately proportional to the exchange         surface area (Z) and therefore to the quantity of food items.

Throughout the phase 22 identified by the square with the broken-line outline where there is marking of the food or food items, there is no reversal of the cycle of delivery of the electrical power (the electrical power/energy delivered to the elements remains maximum).

It is preferably the interval during which the analysis phase (B1, broken line square 22, FIG. 4) is performed: values Y and/or Z, calculated time T.

Regarding the estimation of the surface area (Z) occupied by the food items, FIGS. 5, 6 show respectively:

-   -   the trend of the temperature detected as a function of time and         of said occupied surface area,     -   the trend of the slope of the curve 2 as a function of time and         of the occupied surface area.

In FIGS. 5, 6, the origin of the time (T=0) is the moment when the food item is placed in the heating apparatus, i.e. here (as indicated in FIGS. 1 and 4), the start of the step of cooking of the food item (B).

In FIG. 5, the curves 23, 24, 25 correspond respectively to the steak cases 1, 2, 3. The circles 26, 27, 28 show the respective slope cancelations.

In FIG. 6, the y axis corresponds to the slope (in ° C./s), the x axis is the time (in s).

The curves 29, 30, 31 correspond respectively to the steak cases 1, 2, 3. The circles 33, 35, 37 show the respective slope cancelations (passage through the time x axis).

The analysis of the slope concerned makes it possible to reveal that there are correlations between:

-   -   the exchange surface area and the minimum slope, or the         temperature drop at a given instant,     -   the exchange surface area and the instant when the slope is         canceled (instant when the losses linked to the exchanges         between the food items and the plate have been compensated).

The second relationship (FIG. 6) is deemed more reliable because it is less dependent on the accuracy of the calculations (see dispersion on curve with a steak) and on the position of the sensor on the plate.

It is then possible to consider two methods for estimating the occupied surface area:

-   -   establishing, via a series of experiments conducted in the         factory, before the marketing of the apparatus, the affine         function (y=ax+b) which links the occupied surface area to the         instant when the slope reverses,     -   identifying three areas:         -   area A, plate with low load (⅓ of the plate occupied),         -   area B, plate with average load (⅔ plate),         -   area C, plate fully loaded ( 3/3 plate),     -   then testing the correspondence of the system to one or other of         these three areas.

This method is potentially easier to synchronize with the communication to the user of the corresponding information (indicator 79).

In this case:

-   -   it is essential for the sensor 11 to be positioned on an area         without food, such as the perimeter of the plate,     -   the following are taken into account, as explained above:         -   the existence of a correlation between the reversal of the             temperature trend slope detected by this sensor and the             exchange surface area between the heating plate concerned             and the food (the food items) positioned against said plate:             passage through a zero trend slope; see above,         -   the existence of a correlation between the minimum slope and             said exchange surface area.

In the above, it will have been understood that two methods were therefore considered for estimating the occupied surface area:

-   -   a first able to use only a single temperature sensor 11 remotely         cited at the periphery of the plate concerned, and therefore         with the existence of a relationship between the surface area         occupied by the interposed food and the quantity of energy to be         provided to compensate the losses (time observed for slope of         the curve 2 equal to 0), or a greater or lesser temperature drop         (temperature threshold), or a faster or slower temperature drop         (slope threshold),     -   a second using a number of temperature sensors, such as 11 a, 11         b, distributed on or under the plate concerned, and then with         the presence or not of food (food items) approximately of two,         three, even four sensors.

It should also be noted that, if the temperature sensor(s) 11 or 11 a, 11 b is (are) positioned in such a way that it (they) detects (detect) the temperature of the cooking plate (here upper plate) which comes into contact with the food only when the two plates 61, 63 are displaced relative to one another to close the apparatus (moment when the cooking time=0), it will then be possible to have two information items to trigger the start of the cooking (phase B): the one from the temperature sensor or sensors and the one from the thickness sensor.

In FIG. 7, it will also be noted that the cooking apparatus 60 of meat grill type therefore comprises the lower 61 and upper 63 heating plates, as follows:

-   -   the means 65 for measuring the thickness (Y) of one or more food         item(s) (here called “food” 80), such as the abovementioned         steak(s) (these means 65 are linked functionally to the means 66         for the relative convergence/separation of the plates 61, 63);     -   the selection means 67 for selecting, from a number of presets,         the degree/temperature (X) of internal cooking desired for the         food;     -   means 69 for estimating the surface area (Z) occupied by the         food on one of the heating plates; and     -   means 71 for calculating the cooking time (T) for the food.

A cooking chamber 600 for the food (FIG. 7) is defined between the lower 61 and upper 63 heating plates.

The means 69 for estimating the surface area (Z) comprise the abovementioned temperature sensor 11 or sensors 11 a, 11 b.

In order to best achieve the estimation of the surface area (Z) occupied by the food 80, it is also recommended that the means 71 for calculating the cooking time (T) for the food comprise the microcontroller 73 configured to determine the slope of the temperature curve obtained from the abovementioned temperature measurements.

And, to the same end, it is also recommended that, with these temperature measurements, this microcontroller, or another 75:

-   -   regulate the temperature of the heating plate 61 or 63, and     -   change the quantity of energy to be supplied, via the element or         elements 10, as a function of the size of the surface area         occupied by said food items on the heating plate concerned, in         order therefore to compensate the temperature drops linked to         the placement of these food items between the plates.

The microcontrollers 73, 75 can be combined in a central microcontroller 77. The microcontroller(s) is/are linked to the abovementioned means 65, 66, 67, 69/11 (or 11 a, 11 b), 70, 71, 72, 79 and to the elements 10, to control them. Regarding the inclusion of the internal degree (X) of cooking to be achieved for the food, it has already been understood that it is possible to dispense with the abovementioned step of selection by the user of one of said temperatures stored in memory for this purpose.

The second block diagram scheme below details this case (it is recalled that the abovementioned steps of storage in memory 72, in the factory, of data, algorithms, etc, as mentioned above, are performed identically in this case).

Thus, when the user decides to use the apparatus that he or she has just bought, he or she simply has to engage the latter which is set to preheating mode, in the way already explained.

The following then takes place:

-   -   when the apparatus is operating and to achieve an internal         cooking of the food to a greater or lesser degree then desired         by a user, the user places the food in contact with the heating         plate or plates, such as 61, 63,     -   the apparatus then calculates a first cooking time (T) for the         duly positioned food, as a function of the lowest         temperature (X) out of those stored in memory,     -   at the end of this calculated first cooking time (T), the         apparatus indicates to the user that the corresponding cooking         has been achieved (via, for example, the indicator 79), then:     -   if the user does not remove the food, the apparatus         automatically applies a calculated second cooking time (T) for         the food, as a function of the second in ascending order of said         temperatures stored in memory (X); it will indeed be understood         that this second cooking time will make it possible to increase         the cooking of the food which will thus be cooked more,     -   at the end of this calculated second cooking time (T), the         apparatus again indicates to the user that the corresponding         cooking has been achieved,     -   and so on.

As already explained, the apparatus will, during operation:

-   -   measure the thickness (Y) of the food then positioned against         said heating plate and/or estimate the surface area (Z) occupied         by this food on this heating plate,     -   calculate the cooking time (T) for the duly positioned food,         based:         -   in addition to said internal cooking temperature (X) out of             those stored in memory,         -   on the thickness (Y) of the food and/or on the surface             area (Z) occupied by the food.

For the remainder, the explanations have already been given; they remain valid.

It should however be noted that here it is considered that a cooking apparatus that is heated electrically, by elements, would address the issues already described, provided that it comprised:

-   -   in addition to at least one heating plate to position the food         to be cooked, and in conjunction with a microcontroller (such as         73, 75, 77) provided in the apparatus,     -   means for estimating a surface area (Z) occupied by the food on         the heating plate, via at least one temperature sensor (such as         11, 11 a, 11 a) which:         -   regulates the temperature of the heating plate for which it             measures the temperature, and         -   changes the quantity of electrical energy to be supplied, as             a function of the size of the surface area occupied by the             food on the heating plate, in order to compensate the             temperature drops linked to the placement of the food, or of             the food items, on one of the heating plates, or between             these heating plates.

The means for estimating a surface area (Z) will be able to be those of the description on the preceding pages.

Regarding the apparatus that is the subject of the present topic, it could also be an apparatus comprising only a single heating plate for cooking food by contact.

A cooking pan or any cooking utensil with a cap receiving on contact with it a food to be cooked (casserole, cooking pot, etc) should be able to be used, provided that it would be linked to a controllable heat source, as will have been understood from the above.

Notably in this case, provision could be made for the means for measuring the thickness (Y) of the food placed in contact with the heating plate to be a cover that can be positioned movably on the utensil and provided with the appropriate sensor already described. The cover could be annular.

To favor the food/heating plate(s) contact, each plate will in any case, preferably be full. A grill solution would not then be suitable.

In the above, with reference to the solutions illustrated, provision has been made for the or each (useful) value of internal cooking temperature (X) for the food to be prestored in the memory of the apparatus, in the factory, before the first operational use of this apparatus. Provision could however be made for this (these) data to be input into memory 72 by the user, for example via the interface 67. Thus, it is possible to provide for the user to enter into memory 72 a cooking temperature value (X) of 45° C., for a meat that is desired to be rare. In this case, it would be possible for there not to be, in the factory (therefore before the marketing of the apparatus), any storage in memory notably of the different internal cooking temperature(s) (X) for the food.

It will also be noted that, used alone, independently of the combination of the other abovementioned features, the following method also addresses the issues described above.

A method for implementing a cooking apparatus for a food, cooked electrically and comprising at least one heating plate against which the food is positioned (for cooking by contact), said method comprising at least one step of estimation of the surface area (Z) occupied by the food on said heating plate, this step comprising a sub-step of measurement of the temperature of said heating plate by at least one temperature sensor, and a sub-step of determination of the slope of the temperature curve obtained from measurements of at least one temperature sensor, said slope making it possible to determine whether said surface area of the heating plate is occupied by the food.

It is recommended that the temperature measurements on said heating plate be conducted by the abovementioned sensor(s) 11/11 a, 11 b positioned as indicated.

The same comment applies as above regarding the interesting use alone, independently of the combination of the other abovementioned features, of one or other of the following methods, which also address the issues described above:

-   -   a method for implementing a cooking apparatus heated         electrically and comprising at least one heating plate on which         a food is positioned (for cooking by contact), said method         comprising a step of preheating A) of the apparatus followed by         a step of cooking of the food B), the start of the cooking         step B) being detected by a lowering beyond a predetermined         threshold of the temperature of the heating plate,     -   a method for implementing a cooking apparatus heated         electrically and comprising at least one heating plate on which         the food is positioned (for cooking by contact), said method         comprising a step of calculation by the apparatus of the cooking         time for the food as a function of at least one internal cooking         temperature value (X) for the food prestored in the memory of         the apparatus before its first operational use. 

1. A method for implementing an apparatus for cooking a food, comprising at least one heating plate for heating the food upon its contact, wherein the method comprises: storage in a memory of the apparatus of different internal cooking temperatures (X) for the food, to achieve an internal cooking of the food to a greater or lesser degree as then desired by a user, a placing of the food in contact with the heating plate or plates, then, a calculation of a first cooking time (T) for the duly positioned food, as a function of the lowest temperature (X) out of those stored in memory, at the end of said calculated first cooking time (T), an indication to the user, by the apparatus, that the corresponding cooking has been achieved, then: if the user does not remove the food, the application by the apparatus of a calculated second cooking time (T) for the food, as a function of the second in ascending order of said temperatures stored in memory (X), at the end of this calculated second cooking time (T), another indication to the user, by the apparatus, that the corresponding cooking has been achieved, and so on.
 2. The method for implementing an apparatus for cooking a food, such as a meat grill, comprising at least one heating plate for heating the food upon its contact, wherein it comprises: a storage in memory of the apparatus of different internal cooking temperatures (X) for the food, to achieve an internal cooking of the food to a greater or lesser degree, as then desired by a user, a selection by the user of one of said temperatures (X) and a placing of the food in contact with the heating plate or plates, then, a calculation of the cooking time for the food as a function of the selected temperature (X), at the end of the calculated cooking time (T), preferably an indication by the apparatus that the desired cooking has been achieved.
 3. The method as claimed in claim 1, wherein, during said operation of the apparatus to achieve the desired internal cooking, the following are performed: a measurement of the thickness (Y) of the food then positioned against said heating plate and/or an estimation of the surface area (Z) occupied by this food on the heating plate, the calculation of the cooking time (T) for the duly positioned food, based: in addition to the selected cooking temperature (X), on the thickness (Y) of the food, and/or on the surface area (Z) occupied by the food.
 4. The method as claimed in claim 1, wherein the or each internal cooking temperature value (X) for the food stored in memory of the apparatus is prestored in the factory, before the first operational use of the apparatus.
 5. The method as claimed in claim 1, wherein, during said operation of the apparatus, the food is positioned between a plurality of said heating plates, on their contacts.
 6. The method as claimed in claim 3, wherein the calculation of the cooking time (T) for the food is a function of said surface area (Z) occupied by the food, which is obtained by heating plate temperature measurements.
 7. The method as claimed in claim 6, wherein, to estimate the surface area (Z) occupied by the food, there is measured, by at least one temperature sensor and following the placing of the food in contact with the heating plate or plates, the temperature of the or of one of the heating plate(s), and the variation of the measured temperature evolving therefrom is compared to at least one reference threshold.
 8. The method as claimed in claim 1, wherein the cooking time (T) for the food is obtained by a quadratic or linear correlation calculation method.
 9. The method as claimed in claim 1, wherein it comprises, before the food is placed in contact with the plate or plates, a step (A) of preheating of the apparatus followed by the step (B) of cooking of the food, the start of which is detected by a lowering beyond a predetermined threshold of the temperature of the or of one of the heating plates.
 10. The method as claimed in claim 6, wherein the calculation of the cooking time (T) for the food is a function of said surface area (Z) occupied by the food and, to estimate this surface area, a single temperature sensor is used, which, following the placing of the food in contact with the plate or plates, measures the temperature of at least one of said plates, away from the area of contact of the food, and the measured temperature variations which evolve therefrom or a time that is then calculated until a stabilization of the measured temperature, after said placement in contact, are compared to at least one threshold.
 11. The method as claimed in claim 6, wherein the calculation of the cooking time (T) for the food is a function of said surface area (Z) occupied by the food and, to estimate this surface area, a number of temperature sensors are used which, following the placing of the food in contact with the plate or plates, measure the temperature of at least one of said plates, in the area of contact of the food, and the measured temperature variations which evolve therefrom or a time that is then calculated until a stabilization of the measured temperature, after said placement in contact, are compared to at least one threshold.
 12. The method as claimed in claim 3, wherein, during the step or steps of estimation of the surface area (Z) occupied by the food and/or of the thickness (Y) of the food, and/or of the calculation of the cooking time (T) for the food, there is marking of the food, with an electrical power delivered by the apparatus which is maximum.
 13. The method as claimed in claim 1, wherein it comprises at least one of the following steps: selection of the category of the food to be cooked, and/or selection of the frozen state of the food, and/or selection of a desired grill marking of the food.
 14. The method as claimed in claim 13, wherein the cooking temperature (θ) for the food and the preheating temperature (θ′) are a function of said selection made.
 15. The method as claimed in claim 1, wherein, after having positioned the food in contact with the plate or plates, a thickness (Y) of the food is measured and, as a function of this measurement, the cooking of the food is triggered or not by the calculation of the cooking time.
 16. A cooking apparatus for implementing the method as claimed in claim 1, the apparatus comprising at least one heating plate for heating the food upon its contact, wherein it comprises, to achieve an internal cooking of the food to a greater or lesser degree as desired by a user: a memory for storing different internal cooking temperatures (X) for the food, means for measuring the thickness (Y) of the food then positioned in contact with the heating plate or plates and/or means for estimating the surface area (Z) occupied by this food on the or one of the heating plates, means for calculating at least one cooking time (T) for the duly positioned food, based: on at least one of the internal cooking temperatures (X) out of those stored in memory, and on the thickness (Y) of the food, and/or on the surface area (Z) occupied by the food, and means for indicating to the user, by the apparatus, that the corresponding cooking has been achieved. 